1. Field
The present invention pertains to a cord locking mechanism for use in small systems, especially medical devices, such as heart valve repair apparatuses, implantable devices, devices with length adjustable devices, devices with telescoping sections, grasping devices, devices with deflecting sections or other devices that can be actuated by a cord. Additionally, the cord locking mechanism may be used to release or retrieve a device.
2. Discussion of Related Art
There are many devices and medical devices that are actuated, adjusted, lengthened, or shorten by actions of a cord, filament, wire or other elongated member (these will be referred to as a cord in subsequent descriptions) included within the devices. For instance, some medical devices include a telescoping device to provide flexibility in length for the medical devices. These medical devices typically include cords/wires used to adjust the length of the telescoping device. In other examples, many medical devices employ a locking mechanism that locks a cord/wire included therein to maintain the shapes and/or position of the medical devices or to restrain the devices in a particular position such as those described in U.S. Pat. No. 4,128,100 and U.S. Pat. No. 6,402,781. Further, medical devices such as a deflectable catheter may also use a cord which is locked into position to maintain the shape of the deflectable portion of the deflectable catheter.
Locking devices for cords are generally large, complicated and difficult to operate, especially for percutaneous medical applications. The smallest and simplest available cord locking device mechanisms are demonstrated by the configurations found on common cable ties, but these designs do not allow the cord to move freely in both directions until locking is desired. Without the ability to move freely until locking is desired, an inadvertent and/or transitory over-adjustment cannot be reversed. In addition, these locking mechanisms cannot be easily unlocked. Such over-adjustments can be injurious and/or render the medical device ineffective or less effective than an optimum adjustment, so these available designs are often not safe or practical in most medical applications. A number of other locking devices involve a biasing spring and other more complex features and mechanisms to lock the cord in position. The more elements required in the design of cord locking devices, the greater the risk of failure of, the larger the size of, and the more expensive the locking devices.